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Robber Fly - Efferia

Robber Fly - Efferia
New Vernon, Morris County, New Jersey, USA
July 28, 2008
Size: 1 inch
Robber Fly feeding on a small fly. Probably from Promachus. Maybe Promachus fitchi?

Moved from Efferia.

I'm just getting into these guys, but it looks more like Efferia aestuans to me.

Robber fly
The orange tibia are consistent with Efferia but the abdomen seemed to look more like the pictures that i have of Promachus and the Emerald eye seemed to confirm.
What are the defining features?

swordlike ovipositors are only in the Efferia group. Eye color is not reliable. And Promachus have elongate abdomens in the female but they have the distinctive step shape made from several segments.

And Promachus fitchii is an endangered beast in the NE now.

Robber fly
Thank you for the help.
some of my references are old and maybe out-of-date.

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